Chiller Plant Commissioning. Joseph Lorino, PE, LEED AP Senior Partner April 22, 2008

Transcription

1 Joseph Lorino, PE, LEED AP Senior Partner April 22, 2008

2 Introduction Presentation: Applicable to the commissioning of new chiller plant installations or expansions Concentrate on key Cx elements to address and CA responsibilities during: Pre-Design Phase Design Phase Construction Phase Occupancy & Operations Phase

3 Introduction Encourages the need for a team effort throughout the project Includes Owner, Design Professionals, Contractors, Manufactures, etc. NOT a step-by-step procedure on how to Cx a chiller plant!

4 Long Term Issues Failure to introduce Cx early in the project may lead to: Low plant efficiencies Higher than anticipated construction costs Higher long term operating & maintenance costs Excessive plant downtime Low availability factors Increased crisis repairs Untrained plant personnel End user complaints!

5 ASHRAE Guideline Commissioning Process: A quality focused process for enhancing the delivery of a project. Process focuses upon verifying and documenting that the facility and all of its systems and assemblies are planned, designed, installed, tested, operated & maintained to meet the Owner s Project Requirements (OPR).

6 OPR Written document that details the functional requirements of a project and the expectations on how it will be used & operated Includes project goals, measurable performance criteria, cost considerations, benchmarks, success criteria & supporting information. Considered the most important document in Cx process!

7 OPR Should include amongst others: Owner directives Restrictions User requirements Occupancy requirements & schedules Training requirements O&M criteria Equipment maintainability expectations Energy efficiency goals Adaptability to future expansion Existing systems integration Accessibility requirements

8 OPR CA s responsibility to facilitate the development & documentation of the OPR. Work closely with project team to develop Must be updated throughout the project Should be echoing in the back of team member s minds! OPR

9 Pre-Design Phase Ideal time to select & introduce Commissioning Authority (CA) to project Allows project team to familiar with Cx process Otherwise, CA may be viewed as outsider CA plays advisory role in conceptual process Issues identified early before affecting later stages

10 CHW User Needs Chiller plant designed to meet various occupants and building needs Must be clearly defined in OPR! CA should assist project team to ensure plant performance meets user requirements Leads to Basis of Design Otherwise does not make sense to build it in the first place!

11 Pre-Design Data Cooling coil performance characteristics Plant must be designed to meet these requirements High efficiency DELTA T plant must be capable of properly supplying these coils May require lower CHW supply temperatures, flow balancing or coil replacement Historical CHW load profile Peak days Used to properly size chillers Load variations may lead to different chiller capacities Higher efficiencies above 50% load

12 Pre-Design Data CHW end user schedule, pressure, temperature, etc. Process vs. comfort loads Water-side free cooling options? Drastic load drops may require pony chiller Future CHW system growth Plant size & related piping Rigging paths, future valves & connections Future equipment locations, spare electrical connections, etc.

13 Pre-Design Data Parallel vs. Series configurations Affects plant layout CHW load reduction analysis considered Leads to smaller equipment, lower costs! Chiller prime mover options may be limited Steam, electric, diesel or gas engine, etc. Utility availability Elimination leads to a simpler LCA Allowable emissions levels

14 Pre-Design Data Redundancy requirements (OPR) Cooling tower capacity if lower ECWT is being considered to increase efficiency Plant efficiency goals Full load efficiency, IPLV, etc. Feasibility of water-side free cooling Central plant PFHX or local air cooled unit?

15 Pre-Design Data Hybrid plant for peak load shaving O&M staff training Sophisticated equipment may require detailed training May also require costly outside service for future maintenance for items such as engines, turbines, VSD s, etc.

16 Design Phase CA responsibilities: Attend design meetings Formally review & comment on various stages of design Update OPR Develop & update Cx Plan Include Cx requirements in CD s Define training requirements Integrate Cx in project schedule Begin developing test procedure

17 Design Phase Assist in chiller selection based on load profile Advise on plant layout. Ensure adequate space for: Routine maintenance Tube cleaning Re-tubing condenser & evaporator bundles Rigging of motors, compressors, turbines, etc. Proper heat rejection Future equipment

18 Design Phase Review & verify pump manufacturer curves. Ensure pumps operate at point of peak efficiency Premium efficiency motors chosen Ensure redundancy requirements are met for maintenance & repair

19 Design Phase Cooling tower (CT) wet bulb conditions prevalent to plant area must be understood & utilized Most important when lowering ECWT to increase chiller efficiency Under sizing CT results in reduced chiller capacity & lowered efficiency

20 Design Phase CHW temperature reset must be coordinated with BMS. May lead to higher energy consumption Suggestion of temporary bypass across chiller sections to protect tubes during chemical cleaning & flushing Installation of metering devices to future monitoring of plant performance Review of valve amount & locations for proper operation

21 Design Phase Variable flow primary CHW systems require a bypass to maintain minimum flow Sequence of operation review conforms with OPR Factory test requirements Chiller ARI Standard 550/ Pumps Hydraulic Institute ANSI/HI 1.6 Cooling Tower CTI Manual

22 Design Phase Plant training requirements must be clearly conveyed in CD s. Include: Classroom location Instructor qualifications Classroom time vs. field time Number of sessions Multiple shifts Length of each session Training syllabus Handout requirements

23 Construction Phase CA responsibilities: Installation, field inspections & testing meet OPR Review submittals for adherence to OPR Perform field observation inspections Develop & witness equipment factory testing Develop commissioning checklists Develop test procedures Witness testing Identify & track issues Develop Systems Manual Verify O&M training

24 Construction Phase Compare field installations to shop drawing for additional bends and fittings. May affect pump performance Compare pump submittals to design schedules Variable flow pumps should include curves at different speeds Chiller submittals should include specified performance data Review valve installations for operations Valves 7 FT AFF should include chain operators

25 Construction Phase Minimum CHW flows through evaporator must be tested and noted. VSD s output must not go below this value Evaporator flow switch must be set & tested to trip chiller below minimum flow Proper duty balancing valves should be installed

26 Construction Phase Chemical cleaning and flushing should occur after hydrostatic testing. Corrosion inhibitor immediately afterwards Proper floor drain installation Tube cleaning or punching areas Pump seal drains Chemical shot feeder tanks Steam turbine blow down drains

27 Tube Cleaning

28 Construction Phase Pump performance testing: individual & parallel scenarios Chiller performance testing off-season does not constitute acceptance Ensure future equipment spaces are kept clear Functional testing of equipment should progress from individual components to overall system Chiller head removal systems should be considered

29 Case Study 7,500 ton Chiller Plant in NYC 4 Chiller of various capacities 4 PCHWP 4 CWP 3 SCHWP 8 Cooling Tower Cells 1 Water-side free cooling PFHX 2 Secondary PFHX

30 Issues CA was contracted late in the game No design review No installation inspections Chiller barrels high DELTA P Tube sheets covered with chip scale Did not bypass during cleaning & flushing 3 Primary CHW & CW pumps running for 1 chiller Flow not balanced DPT not field calibrated 3 SCHWP running DPT not field calibrated CWP cavitating NPSH A < NPSH R PFHX s & Cooling Towers not balanced

31 Actions Clean chiller barrels Balance flow through chillers Calibrate all field DPT Balance flow through PFHX s & CT s Reduced CW pump speed, raised CT level

32 Results Less pumps operating Higher chiller efficiency Less tower fans operating Extended free-cooling season ANNUAL SAVINGS: 150,000

33 Occupancy & Operations Phase CA responsibilities include: Facilitating warranty period Coordinating contractor callbacks Continue personnel training Verify systems meet OPR Conduct periodic performance evaluations Complete Systems Manual Complete Final Cx Report

34 Occupancy & Operations Phase Utilize plant kw meters or BMS to evaluate plant performance during partial & peak load conditions Seasonal water-side free cooling testing & training Warranty items tabulated & facilitated by CA

35 Final Commissioning Report THE OLD METHOD Final OPR Plant Basis of Design Plant systems & narratives Design review comments Submittal review comments Final sequence of operations Cx Process & Plan Completed Cx checklist Test Data

36 Final Commissioning Report Final Cx Report Environmentally Conscience Method Training materials Systems Manual Meeting minutes Warranty review information Issues or deficiency log

37 Conclusion Chiller, Cooling Tower & Pump Commissioning Checklists Draft Chiller Plant Acceptance Procedure Available on NCBC 2008 Proceedings

38 Joseph Lorino, PE, LEED AP Senior Partner 30 Broad Street, 15 th Floor New York, NY